CN101750590B - Method and device for measuring environment temperature change and magnetic induction strength - Google Patents

Abstract

The invention discloses a method and a device for measuring environment temperature change and magnetic induction strength, belongs to the field of photoelectric technology, relates to optical fiber sensing technology, in particular to a method and a device for measuring magnetic induction strength ( or optical fiber Verdet constant) and temperature change based on magneto-optical fiber Bragg optical grating (MFBG). The invention adopts magneto-optical fiber Bragg optical grating, respectively utilizes levorotation and dextrorotation circularly polarized light to emit into MFBG according to intrinsic sensing mode and reflectivity and transmission property, and realizes measuring magnetic induction strength ( or optical fiber Verdet constant) and temperature change simultaneously by detecting luminous power reflection (or transmission) circularly polarized light of MFBG, thus realizing multiple parameter incoherent detection, and having the advantages of convenience, easiness and omission of temperature compensation.

Description

The measuring method of a kind of variation of ambient temperature and magnetic induction density and device

Technical field

The invention belongs to field of photoelectric technology, relate to optical fiber sensing technology, relate in particular to magnetic induction density (or optical fiber V erdet constant) and the measuring method and the device of temperature variation based on magneto-optic optical fiber Bragg raster (MFBG).

Background technology

Optical fiber sensing technology is to be accompanied by the development of light transmitting fiber and Fibre Optical Communication Technology and a kind of novel sensing technology that develops rapidly.It is to be the carrier of treating measurement information with light signal, is transmission medium and sensing medium with optical fiber, and the form of measured information with light signal extracted.Specifically, Fibre Optical Sensor is to survey a kind of device of various physical quantitys through the characteristic parameter (like light intensity, wavelength, phase place, amplitude etc.) that extracts light wave in the optical fiber with extraneous factor (like temperature, pressure, magnetic field, electric field, displacement, the acceleration etc.) relation that changes directly or indirectly.

Compare with traditional electric transducer, Fibre Optical Sensor has many good qualities, and is good, corrosion-resistant, convenient and safe like: 1. anti-electromagnetic interference (EMI), electrical insulating property; 2. highly sensitive; 3. in light weight, volume is little, Miniaturized; 4. transmission capacity is big, measuring object is extensive; 5. cost is low; 6. be convenient to multiplexing, be convenient to networking, can realize Remote.

Fibre optic magnetic field sensor is a kind of Fibre Optical Sensor of measuring magnetic field or electric current, can realize based on different principle.The fibre optic magnetic field sensor based on magnetostriction principle is to utilize magnetostriction materials that thereby the disturbance of optical fiber is changed phase of light wave detection Weak magentic-field; But because magnetostrictive effect is as mechanical effect; Its HF-response is relatively poor, and relatively stricter to the requirement of magnetostriction materials.People have also developed various interferometric optical fiber sensors based on the interference of light Research on Principle; Like fibre optic magnetic field sensor based on the Fabry-Perot interferometer; Fibre optic magnetic field sensor based on the Micelson interferometer; Based on fibre optic magnetic field sensor of Mach-Zehnder interferometer etc., these interferometric optical fiber sensors are fit to be applied to the detection of dynamic alternating magnetic field.

On the other hand, because the disturbance in the external world is inevitable to the influence of magnetic-field measurement precision in the practical application, wherein influence of temperature variation is especially outstanding, so the cross-sensitivity in temperature and magnetic field is an important bottleneck in the research fibre optic magnetic field sensor.For obtaining high-precision measurement result, people have proposed various fibre optic magnetic field sensors with temperature compensation function.A kind of is to adopt temperature control system to make its duty that remains on constant temperature to the temperature sensor in the fibre optic magnetic field sensor, as utilizes MCU driving semiconductor cooler noise spectra of semiconductor lasers to carry out temperature control; Another kind be in the compensated optical fiber magnetic field sensor temperature variant Verdet constant to guarantee the degree of accuracy of magnetic-field measurement.They belong to extrinsic sensing mode, and carry out complicacy.

Magneto-optic optical fiber Bragg raster (MFBG) has higher magneto-optical property; Its method for making has several kinds; Make its REE with high magneto-optic coefficient (like Tb, Pr etc.) as in optical fiber Bragg raster, mixing, perhaps on the YIG optical fiber that draws, write Bragg grating etc.MFBG is under the forwards/reverse guided wave coupling interaction that polarization mode conversion of inducing based on magneto-optic effect and grating cause; Have and traditional fiber grating different features: (1) in no linear birefringent magneto-optic fiber grating, its eigenmode is a circularly polarized light; (2) magnetic field and variation of temperature can make propagate in the magneto-optic fiber grating about revolve eigenmode the Bragg wavelength the mobile of opposite and equidirectional taken place respectively; (3) magneto-optic effect has changed the bandgap structure of linearly polarized light in traditional non magnetic fiber grating, and dispersion characteristics are abundanter.Utilize this special construction of magneto-optic fiber grating and intrinsic characteristic, can realize magnetic-field measurement, current sense and realize polarization mode conversion and control or optical polarization etc.In the magneto-optic optical fiber Bragg raster, Faraday effect can cause the rotation (polarization mode conversion) of plane of polarization, and the magneto-optic stiffness of coupling can be regulated through externally-applied magnetic field.

Summary of the invention

For overcoming the deficiency of existing optical fiber magnetic field sensing method based on ordinary optic fibre grating and temperature compensation; The invention provides a kind of based on the variation of ambient temperature of magneto-optic optical fiber Bragg raster (MFBG) and the measuring method and the device of magnetic induction density; It is based on the intrinsic sensing mode of magneto-optic fiber grating; Can measure environment magnetic induction density (or optical fiber V erdet constant) and temperature variation simultaneously; In detection, can eliminate Influence of Temperature automatically, measuring method is simple, implement conveniently.

The present invention utilizes frequency spectrum under linear symmetric property that MFBG band gap edge frequency spectrum had and the action of a magnetic field that the selectivity principle of circular polarization state is realized what magnetic field sensing or optical fiber V erdet constant were measured.The characteristic of MFBG can be used grating coupling coefficient κ _g=k ₀Δ n _gWith magneto-optic coupling coefficient κ _m=k ₀Δ n _m(=Φ _F=V _BB) two parameter characterizations, wherein Δ n _gWith Δ n _mBe respectively corresponding refraction index changing, k ₀=2 π/λ is a Boltzmann constant, Φ _FBe faraday's rotation angle, V _BBe respectively Verdet constant and induction level with B.The reflection of MFBG or the shape of transmission spectrum are exactly by κ _gAnd κ _mDecision.Fig. 1 has provided transmission spectrum and the reflectance spectrum of circularly polarized light through even MFBG, and left-handed spectral line with right-circularly polarized light does not overlap when having magnetic field.Visible by figure, evenly the spectrum of MFBG is symmetrical about centre wavelength, and has fine linearity at the band gap edge.

Technical scheme of the present invention is following:

The measuring method of a kind of variation of ambient temperature and magnetic induction density, as shown in Figure 2, may further comprise the steps:

Step 1: the magneto-optic optical fiber Bragg raster is placed under magnetic shielding and the constant temperature (being equivalent to environment magnetic induction density B=0 and variation of ambient temperature Δ T=0), adopting wavelength respectively is λ ₁And λ ₂Left-hand polarization light and right-handed polarized light incide the magneto-optic optical fiber Bragg raster, measure through the left-hand polarization light of magneto-optic optical fiber Bragg raster reflection (or transmission) and the luminous power P of right-handed polarized light ₀₁And P ₀₂

Step 2: the magneto-optic optical fiber Bragg raster is placed under the condition of magnetic field and known temperature change DeltaT of known magnetic induction density B, adopting wavelength respectively is λ ₁And λ ₂Left-hand polarization light and right-handed polarized light incide the magneto-optic optical fiber Bragg raster, measure through the left-hand polarization light of magneto-optic optical fiber Bragg raster reflection (or transmission) and the luminous power P of right-handed polarized light ₁And P ₂

Step 3: by

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H200910167917XE00011.png"\; state="\{\{state\}\}">P</figure-callout>}}_1=P_{01}+\mathrm{\&Delta;}{P}_B+\mathrm{\&Delta;}{P}_T\\ P_2={\mathrm{<figure-callout\; id="02"\; label="P"\; filenames="H200910167917XE00021.png"\; state="\{\{state\}\}">P</figure-callout>}}_{02}+\mathrm{\&Delta;}{P}_B-{\mathrm{\&Delta;P}}_T\end{array}\right.---\left(1\right)$

Wherein, Δ P _BFor the magneto-optic optical fiber Bragg raster that is caused by magnetic induction density in the environment reflects the variable quantity of the polarized light luminous power of (or transmission), Δ P _TReflect the variable quantity of the polarized light luminous power of (or transmission) for the magneto-optic optical fiber Bragg raster that causes by temperature variation in the environment;

Can get

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H200910167917XE00011.png"\; state="\{\{state\}\}">P</figure-callout>}}_1+P_2=2\mathrm{\&Delta;}{P}_B+P_{01}+P_{02}\\ P_1-P_2=2\mathrm{\&Delta;}{P}_T+P_{01}-P_{02}\end{array}\right.---\left(2\right)$

Step 4: (2) formula by in the step 3 is confirmed P ₁+ P ₂With Δ P _BLinear relationship and P ₁-P ₂With Δ P _TLinear relationship; Simultaneously the magneto-optic optical fiber Bragg raster has such inherent characteristic: the variation delta P of the polarized light luminous power of environment magnetic induction density B and the magneto-optic optical fiber Bragg raster reflection (or transmission) that caused by magnetic induction density in the environment _BLinear, and the variation delta P of the polarized light luminous power of variation of ambient temperature Δ T and the magneto-optic optical fiber Bragg raster reflection (or transmission) that causes by temperature variation in the environment _TAlso linear.Can further obtain P according to the above-mentioned inherent characteristic of magneto-optic optical fiber Bragg raster ₁+ P ₂Linear relationship (as shown in Figure 7) and P with B ₁-P ₂Linear relationship (as shown in Figure 8) with Δ T.

Step 5: when the magnetic field of magnetic induction density B to be measured and temperature variation Δ T to be measured acted on the magneto-optic optical fiber Bragg raster, adopting wavelength respectively was λ ₁And λ ₂Left-hand polarization light and right-handed polarized light incide the magneto-optic optical fiber Bragg raster, measure through the left-hand polarization light of magneto-optic optical fiber Bragg raster reflection (or transmission) and the luminous power P of right-handed polarized light ₁And P ₂, and then obtain P ₁+ P ₂And P ₁-P ₂Value.

Step 6: the P definite according to step 4 ₁+ P ₂Linear relationship and P with B ₁-P ₂With the linear relationship of Δ T, find out the P of step 5 gained ₁+ P ₂And P ₁-P ₂The respectively corresponding magnetic induction density B of value and the value of temperature variation Δ T, the value of gained magnetic induction density B is exactly the size of unknown magnetic induction density B in the step 5, the value of gained temperature variation Δ T is exactly the size of unknown temperatures change DeltaT in the step 5.

The present invention is an inherent characteristic of utilizing MFBG, and the principle that influences of MFBG reflection (or transmission) being composed according to external parameter realizes what magnetic induction density (or optical fiber V erdet constant) and temperature variation were measured.Principle of work is described below:

Shown in Fig. 3 (a), when magnetic induction density B=0 and constant temperature constantly the reflected light of the left-handed and right-circularly polarized light of different wave length overlap with incident light, the catoptrical luminous power of Left-hand circular polarization is P under this original state ₀₁, right-hand circular polarization reflected light luminous power is P ₀₂Characteristic by the magneto-optic fiber grating can be known; The Bragg wavelength of the reflection of polarization that the effect of environmental magnetic field makes (or transmission) light moves; Left-handed composing through the reflection (or transmission) of magneto-optic fiber grating with right-circularly polarized light moves to left respectively and moves to right, and (wavelength is respectively λ to the left-handed and right-circularly polarized light of process magneto-optic grating ₁And λ ₂) luminous power has identical recruitment Δ P during with respect to B=0 _BEqually, temperature also exerts an influence to reflection (or transmission) characteristic of MFBG.Relation by temperature and center Bragg wavelength can know, reflection (or transmission) spectrum (left-handed with right-circularly polarized light) that variation of temperature makes MFBG is to the same direction identical size of drifting about.Visible shown in Fig. 3 (b), left-handedly increase respectively with the right-circularly polarized light luminous power and reduce identical size, delta P _T

If MFBG is under the effect of environment magnetic induction density B and temperature variation Δ T, left-handed reflection (or projection) Output optical power with right-circularly polarized light is respectively P ₁And P ₂, then they can be expressed as respectively $\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H200910167917XE00011.png"\; state="\{\{state\}\}">P</figure-callout>}}_1=P_{01}+\mathrm{\&Delta;}{P}_B+\mathrm{\&Delta;}{P}_T\\ P_2={\mathrm{<figure-callout\; id="02"\; label="P"\; filenames="H200910167917XE00021.png"\; state="\{\{state\}\}">P</figure-callout>}}_{02}+\mathrm{\&Delta;}{P}_B-\mathrm{\&Delta;}{P}_T\end{array}\right.,$ So:

P ₁+P ₂＝2ΔP _B+P ₀₁+P ₀₂

P ₁-P ₂＝2ΔP _T+P ₀₁-P ₀₂

Thus it is clear that, Δ P _B∝ P ₁+ P ₂, Δ P _T∝ P ₁-P ₂Can know by last analysis, when considering magnetic induction density and Influence of Temperature simultaneously, can realize magnetic-field measurement and temperature survey respectively with right-hand circular polarization reflection (or projection) light luminous power sum and extent variation according to left-handed.Thereby draw magnetic induction density B and Δ P _BAnd variation of temperature Δ T and Δ P _TLinear relationship, Here it is based on the principle of the measuring method of the magnetic induction density of MFBG and temperature variation.

Need to prove:

1, in the such scheme, the left-handed wavelength X with right-circularly polarized light of the incident that step 1 adopted ₁And λ ₂Can be identical, also can be inequality.

2, utilize the ultimate principle of technical scheme of the present invention, also can realize the measurement of the optical fiber V erdet constant of MFBG.

Provided by the invention a kind of based on the variation of ambient temperature of magneto-optic optical fiber Bragg raster (MFBG) and the measuring method and the device of magnetic induction density; Intrinsic sensing mode based on the magneto-optic fiber grating; Can measure environment magnetic induction density (or optical fiber V erdet constant) and temperature variation simultaneously; In detection, can eliminate Influence of Temperature automatically, have simple, the implement device characteristic of simple structure of measuring method.

Description of drawings

Fig. 1 is transmission spectrum and the reflectance spectrum of circularly polarized light through even MFBG.

Fig. 2 is a schematic flow sheet of the present invention.

Fig. 3 is the influence that magnetic induction density and temperature variation are composed the reflection (or transmission) of magneto-optic fiber grating.Wherein (a) is the influence of magnetic induction density to reflection (or transmission) spectrum of magneto-optic fiber grating; (b) be the influence of temperature variation to reflection (or transmission) spectrum of magneto-optic fiber grating.

Fig. 4 is the measurement mechanism synoptic diagram of variation of ambient temperature provided by the invention and magnetic induction density.

Fig. 5 is the measurement mechanism synoptic diagram of reflective variation of ambient temperature provided by the invention and magnetic induction density.

Fig. 6 is the measurement mechanism synoptic diagram of transmission-type variation of ambient temperature provided by the invention and magnetic induction density.

Fig. 7 is P ₁+ P ₂Linear relationship with B.

Fig. 8 is P ₁-P ₂Linear relationship with Δ T.

Embodiment

The implement device of the measuring method of variation of ambient temperature and the magnetic induction density based on MFBG provided by the invention; As shown in Figure 4, comprise four unit: polarized light emission unit, magneto-optic optical fiber Bragg raster (MFBG), polarized light detection measurement unit and data processing unit.

According to the transmission and reflection characteristic of magneto-optic fiber grating, the device that the present invention confirms has two kinds: reflective measurement mechanism (as shown in Figure 5) and transmission-type measurement mechanism (as shown in Figure 6).

Embodiment one:

The measurement mechanism of a kind of variation of ambient temperature and magnetic induction density like Fig. 4, shown in 5, comprises polarized light emission unit, magneto-optic optical fiber Bragg raster (MFBG), polarized light detection measurement unit and data processing unit.

Said polarized light emission unit comprises first and second narrow-band light source, first and second optical fiber polarizer, first and second optical polarization controller and light wavelength division multiplexing WDM; The wavelength that first narrow-band light source is sent is λ ₁Light rise through the first optical fiber polarizer and produce left circularly polarized light through first optical polarization controller after inclined to one side; The wavelength that second narrow-band light source is sent is λ ₂Light rise through the second optical fiber polarizer and produce right-circularly polarized light through second optical polarization controller after inclined to one side; Left circularly polarized light and right-circularly polarized light are through synthetic one tunnel output of light wavelength division multiplexing WDM.

Said polarized light detection measurement unit comprises light wave decomposition multiplex device DWDM and first and second photoelectric detector.Two wavelength optical signals that light wave decomposition multiplex device DWDM will import are separately carried out noncoherent detection and opto-electronic conversion by first and second photoelectric detector respectively.Said first and second photoelectric detector is by comprising that the photoelectric detective circuit that photodiode is formed constitutes.

Said data processing unit comprises analog to digital conversion, data acquisition, Computer Processing and display part as a result.The electric signal of polarized light detection output is imported computing machine and is carried out data processing and result's demonstration after data processing unit carries out analog to digital conversion, data acquisition.

Connect through an optical circulator between said polarized light emission unit, magneto-optic optical fiber Bragg raster and the polarized light detection measurement unit: the signal output part of promptly said polarized light emission unit connects the port one of optical circulator; The reflector port of said magneto-optic optical fiber Bragg raster connects the port 2 of optical circulator, and the signal input part of said polarized light detection measurement unit connects the port 3 of optical circulator.

Embodiment two:

The measurement mechanism of a kind of variation of ambient temperature and magnetic induction density like Fig. 4, shown in 6, comprises polarized light emission unit, magneto-optic optical fiber Bragg raster (MFBG), polarized light detection measurement unit and data processing unit.

Said polarized light emission unit comprises first and second narrow-band light source, first and second optical fiber polarizer, first and second optical polarization controller and light wavelength division multiplexing WDM; The wavelength that first narrow-band light source is sent is λ ₁Light rise through the first optical fiber polarizer and produce left circularly polarized light through first optical polarization controller after inclined to one side; The wavelength that second narrow-band light source is sent is λ ₂Light rise through the second optical fiber polarizer and produce right-circularly polarized light through second optical polarization controller after inclined to one side; Left circularly polarized light and right-circularly polarized light are through synthetic one tunnel output of light wavelength division multiplexing WDM.

Said polarized light detection measurement unit comprises light wave decomposition multiplex device DWDM and first and second photoelectric detector.Two wavelength optical signals that light wave decomposition multiplex device DWDM will import are separately carried out noncoherent detection and opto-electronic conversion by first and second photoelectric detector respectively.Said first and second photoelectric detector is by comprising that the photoelectric detective circuit that photodiode is formed constitutes.

Said data processing unit comprises analog to digital conversion, data acquisition, Computer Processing and display part as a result.The electric signal of polarized light detection output is imported computing machine and is carried out data processing and result's demonstration after data processing unit carries out analog to digital conversion, data acquisition.

The signal output part of said polarized light emission unit connects the reflector port of magneto-optic optical fiber Bragg raster, and the signal input part of said polarized light detection measurement unit connects the transmission port of magneto-optic optical fiber Bragg raster.

Claims (5)

1. the measuring method of variation of ambient temperature and magnetic induction density may further comprise the steps:

Step 1: the magneto-optic optical fiber Bragg raster is placed under magnetic shielding and the constant temperature, and adopting wavelength respectively is λ ₁And λ ₂Left-hand polarization light and right-handed polarized light incide the magneto-optic optical fiber Bragg raster, measure through the reflection of magneto-optic optical fiber Bragg raster or the left-hand polarization light of transmission and the luminous power P of right-handed polarized light ₀₁And P ₀₂

Step 2: the magneto-optic optical fiber Bragg raster is placed under the condition of magnetic field and known temperature change DeltaT of known magnetic induction density B, adopting wavelength respectively is λ ₁And λ ₂Left-hand polarization light and right-handed polarized light incide the magneto-optic optical fiber Bragg raster, measure through the reflection of magneto-optic optical fiber Bragg raster or the left-hand polarization light of transmission and the luminous power P of right-handed polarized light ₁And P ₂

Step 3: by

$\left\{\begin{array}{c}{P}_1=P_{01}+\mathrm{\&Delta;}{P}_B+\mathrm{\&Delta;}{P}_T\\ P_2=P_{02}+\mathrm{\&Delta;}{P}_B-{\mathrm{\&Delta;P}}_T\end{array}\right.---\left(1\right)$

Wherein, Δ P _BBe the variable quantity of the polarized light luminous power of reflection of the magneto-optic optical fiber Bragg raster that causes by magnetic induction density in the environment or transmission, Δ P _TVariable quantity for the polarized light luminous power of reflection of the magneto-optic optical fiber Bragg raster that causes by temperature inversion in the environment or transmission;

Can get

$\left\{\begin{array}{c}{P}_1+P_2=2\mathrm{\&Delta;}{P}_B+P_{01}+P_{02}\\ P_1-P_2=2\mathrm{\&Delta;}{P}_T+P_{01}-P_{02}\end{array}\right.---\left(2\right)$

Step 4: (2) formula by in the step 3 is confirmed P ₁+ P ₂With Δ P _BLinear relationship and P ₁-P ₂With Δ P _TLinear relationship; Simultaneously the magneto-optic optical fiber Bragg raster has such inherent characteristic: the variation delta P of the polarized light luminous power of environment magnetic induction density B and magneto-optic optical fiber Bragg raster reflection that is caused by magnetic induction density in the environment or transmission _BLinear, and the variation delta P of the polarized light luminous power of variation of ambient temperature Δ T and magneto-optic optical fiber Bragg raster reflection that causes by temperature inversion in the environment or transmission _TAlso linear; Can further obtain P according to the above-mentioned inherent characteristic of magneto-optic optical fiber Bragg raster ₁+ P ₂Linear relationship and P with B ₁-P ₂Linear relationship with Δ T;

Step 5: when the magnetic field of magnetic induction density B to be measured and temperature variation Δ T to be measured acted on the magneto-optic optical fiber Bragg raster, adopting wavelength respectively was λ ₁And λ ₂Left-hand polarization light and right-handed polarized light incide the magneto-optic optical fiber Bragg raster, measure through the reflection of magneto-optic optical fiber Bragg raster or the left-hand polarization light of transmission and the luminous power P of right-handed polarized light ₁And P ₂, and then obtain P ₁+ P ₂And P ₁-P ₂Value;

Step 6: the P definite according to step 4 ₁+ P ₂Linear relationship and P with B ₁-P ₂With the linear relationship of Δ T, find out the P of step 5 gained ₁+ P ₂And P ₁-P ₂The respectively corresponding magnetic induction density B of value and the value of temperature variation Δ T, the value of gained magnetic induction density B is exactly the size of unknown magnetic induction density B in the step 5, the value of gained temperature variation Δ T is exactly the size of unknown temperatures change DeltaT in the step 5.

2. the measurement mechanism of variation of ambient temperature and magnetic induction density comprises polarized light emission unit, magneto-optic optical fiber Bragg raster, polarized light detection measurement unit and data processing unit;

Said polarized light emission unit comprises first and second narrow-band light source, first and second optical fiber polarizer, first and second optical polarization controller and light wavelength division multiplexing WDM; The wavelength that first narrow-band light source is sent is λ ₁Light rise through the first optical fiber polarizer and produce left circularly polarized light through first optical polarization controller after inclined to one side; The wavelength that second narrow-band light source is sent is λ ₂Light rise through the second optical fiber polarizer and produce right-circularly polarized light through second optical polarization controller after inclined to one side; Left circularly polarized light and right-circularly polarized light are through synthetic one tunnel output of light wavelength division multiplexing WDM;

Said polarized light detection measurement unit comprises light wave decomposition multiplex device DWDM and first and second photoelectric detector; Two wavelength optical signals that light wave decomposition multiplex device DWDM will import are separately carried out noncoherent detection and opto-electronic conversion by first and second photoelectric detector respectively;

Said data processing unit comprises analog to digital conversion, data acquisition, Computer Processing and display part as a result; The electric signal of polarized light detection output is imported computing machine and is carried out data processing and result's demonstration after data processing unit carries out analog to digital conversion, data acquisition;

Connect through an optical circulator between said polarized light emission unit, magneto-optic optical fiber Bragg raster and the polarized light detection measurement unit: the signal output part of promptly said polarized light emission unit connects the port one of optical circulator; The reflector port of said magneto-optic optical fiber Bragg raster connects the port 2 of optical circulator, and the signal input part of said polarized light detection measurement unit connects the port 3 of optical circulator.

3. the measurement mechanism of variation of ambient temperature according to claim 2 and magnetic induction density is characterized in that, said first and second photoelectric detector is by comprising that the photoelectric detective circuit that photodiode is formed constitutes.

4. the measurement mechanism of variation of ambient temperature and magnetic induction density comprises polarized light emission unit, magneto-optic optical fiber Bragg raster, polarized light detection measurement unit and data processing unit;

Said polarized light emission unit comprises first and second narrow-band light source, first and second optical fiber polarizer, first and second optical polarization controller and light wavelength division multiplexing WDM; The wavelength that first narrow-band light source is sent is λ ₁Light rise through the first optical fiber polarizer and produce left circularly polarized light through first optical polarization controller after inclined to one side; The wavelength that second narrow-band light source is sent is λ ₂Light rise through the second optical fiber polarizer and produce right-circularly polarized light through second optical polarization controller after inclined to one side; Left circularly polarized light and right-circularly polarized light are through synthetic one tunnel output of light wavelength division multiplexing WDM;

Said polarized light detection measurement unit comprises light wave decomposition multiplex device DWDM and first and second photoelectric detector; Two wavelength optical signals that light wave decomposition multiplex device DWDM will import are separately carried out noncoherent detection and opto-electronic conversion by first and second photoelectric detector respectively;

Said data processing unit comprises analog to digital conversion, data acquisition, Computer Processing and display part as a result; The electric signal of polarized light detection output is imported computing machine and is carried out data processing and result's demonstration after data processing unit carries out analog to digital conversion, data acquisition;

The signal output part of said polarized light emission unit connects the reflector port of magneto-optic optical fiber Bragg raster, and the signal input part of said polarized light detection measurement unit connects the transmission port of magneto-optic optical fiber Bragg raster.

5. the measurement mechanism of variation of ambient temperature according to claim 4 and magnetic induction density is characterized in that, said first and second photoelectric detector is by comprising that the photoelectric detective circuit that photodiode is formed constitutes.

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